/**
    switch-case 多分支语句

    语法:
       switch(表达式值){
           case 值1:
               语句块1
                [break]  
           case 值2:
               语句块2
                [break]  
           case 值3:
               语句块3
                [break] 
            default
               默认语句块 
       }
 
 */
var num = 10
switch(num){
    case 10:
        console.log('num == 10');
        // break
    case 20:
        console.log('num == 20');
        break
    case 50:
        console.log('num == 50');
        break
    default:
        console.log('没有匹配值');
}
